1. Field of the Invention
This invention relates to pollution removal from sewage by means of a meticulously designed system which enables the system to be contained in compact relatively inexpensive apparatus which is ideally suited for single family dwellings and other units where complex systems are neither desirable nor affordable. While the disclosed system has features and elements which can be utilized in modified arrangements including plants designed to serve larger population segments, it will be appreciated that the elements which make up the subject invention combine to provide a vastly superior means to aerate, flocculate, separate and clarify waste pollutants from their water transport media in a self-contained highly efficient system or plant so much in demand today in rural areas.
The system utilizes aerobic micro-organisms to convert unstable pollutants into stable, non-putrescible compounds. Untreated waste water is combined in an aeration tank with a well aerated activated sludge which is super-abundant with aerobic micro-organisms. The micro-organisms adsorb and absorb suspended and dissolved pollutants from the untreated waste water as they are further stimulated by the addition of dissolved oxygen to reduce the pollutants to stable compounds. The mixed liquor, of micro-organisms and stable compounds is then conveyed into a clarifier tank. In the clarifier, the solids, aerobic micro-organisms and stable compounds, are induced to separate from the water transport media and settle to the bottom of the clarifier. The solids are then returned to the incoming end of the aeration tank as super-abundant micro-organisms.
2. Prior Art
Various types of activated sludge systems are known and have been in use for many years. One widely used such system comprised generally a primary settler, an aerator and a final settler with return sludge being channeled from the final settler to the primary settler and/or the aerator. A variation of such a system was disclosed in U.S. Pat. No. 2,065,123 which issued to J. R. Downs on Dec. 22, 1936.
In more recent systems, two tank processes have been utilized in which an aerator and a clarifier are utilized in combination to treat refuse streams. Systems of this type can be found in U.S. Pat. No. 2,363,176 which issued on Nov. 21, 1944 to J. Gunz and in WATER AND WASTE--WATER TECHNOLOGY by Hammer (John Wiley and Sons, 1975) on page 391.
The common drawback in the use of activated sludge processes in the past has been the inability of designers of such systems to achieve the optimum control of the waste water at all stages during the decomposition period which is of vital necessity if one is to achieve goals necessary to make such a system acceptable by environmental protection standards. More specifically, the waste water treatment must be free of anaerobic deterioration throughout the process. Such action occurs during settling and storage periods when anaerobic micro-organisms thrive without oxygen supply, thus creating anaerobic conditions which are directly opposed to aerobic decomposition or biological action. This anaerobic decomposition or deterioration of the sludge can occur quite quickly such as when sewage is momentarily constrained in depressions and cavities of systems and apparatus, and once anaerobic decomposition occurs, considerably greater quantities of energy, necessitating considerable expense for equipment and power, have to be expanded to reverse the anaerobically sour sludge if a high degree of clarification is to be achieved.
As stated, although the principles of pollution abatement through the use of aerobic micro-organisms are well known, there is not an economical and reliable system available for use in residential or small commercial unit service. Fluid flow considerations have not been developed to the optimum and the existing systems do not effectively mix the raw feed stream together with the sludge material and oxygen to sufficiently treat the wastes nor do they provide apparatus which constrains ingredients in such a manner to provide sufficient time for the actions and separations to occur at the optimum points within the system.